I have always been ambivalent. There are enough sightings, videos, physical trace cases, radar contacts, etc, to suggest that there is something there. But none of the evidence gets anywhere close to the level of certainty that you could say: “Yep, definitely aliens. If you are absolutely convinced that UFOs are alien spacecraft, you are irrational. Conversely, if you are convinced that UFOs are definitely not alien spacecraft, you are equally irrational.